Method of applying a lubricating and friction-reducing layer on the inner surface of a tubular body of metallic material

ABSTRACT

A method for applying a lubricating and friction-reducing layer on the inner surface of a tubular metallic body comprising the steps of applying a lubricating and friction-reducing coating on the inner surface of the body and thereafter subjecting said coating to a deformation calibration by means of a bearer.

United States Patent 1151 3,639,960

Waage Feb. 8, 1972 [54] METHOD OF APPLYING A [58] Field of Search..29/l49.5 NM, 149.5 R, l49.5 PM

LUBRICATING AND FRICTION- REDUCING LAYER 0N THE INNER [561 CM SURFACE OFA TUBULAR BODY OF UNITED STATES PATENTS METALLIC MATERIAL 3,514,8316/1970 Bruch et al. ..29/149.5 NM

lnventor: Bard Meyer Waage, Knivsta, Sweden Assignee: l-labiaKommanditbolag, Knivsta, Sweden Filed: Oct. 14, 1970 Appl. No.: 80,569

Foreign Application Priority Data Primary Examiner-Th0mas l-l. EagerAttarney-Brumbaugh, Graves, Donohue & Raymond [5 7] ABSTRACT A methodfor applying a lubricating and friction-reducing layer on the innersurface of a tubular metallic body comprising the steps of applying alubricating and friction-reducing coating on the inner surface of thebody and thereafter subjecting said coating to a deformation calibrationby means of a bearer.

3 Claims, 3 Drawing Figures OCL 20, 1969 Sweden ..l4378/69 US. Cl. ..29/149.5 NM

Int. Cl. ..B23p 11/00, 821d 53/ 10 METHOD OF APPLYING A LUBRICATING ANDFRICTION-REDUCING LAYER ON THE INNER SURFACE OF A TUBULAR BODY OFMETALLIC MATERIAL This invention refers to a method of applying alubricating and friction-reducing layer on the inner surface of atubular body of metallic material, a lubricating and friction-reducingcoating being arranged on the inner sheath surface of the tubular body,and thereafter being subjected to a deformation calibration by means ofa bearer. It may, for example, be used with advantage in the manufactureof self-lubricating bushings in combination with shaft pins on, forexample, spring coils for lorries, king pins and all movable componentsfor industrial and even marine purposes, where the static and dynamicfriction is of great importance.

As is well known, in the manufacture of lorries bushings of bronze withpins or normal steel have been used for the spring coils. A considerabledisadvantage with such bushings is that after being in use for sometime, particularly under difficult conditions, they have a serioustendency to corrode, for example because of gravel and salt, etc., fromthe roads. This often causes serious damage to the shaft pins and thus areduced lubrication ability. Because of the formation of rust suchbushings must be replaced often and if this is not done in time theremay be serious consequences. There are similar disadvantages when thesebushings are used in other fields, for example in ships where the waterconstitutes a great corrosion risk. In certain cases the rust formationbrought about has been so great that it has even been necessary to cutthe bushing when dismantling.

Among the objects of this invention is the provision of a method wherebythe arrangement of said friction-reducing and lubricating coating may becarried out with greater economy and efficiency than herebeforepracticed and furthermore at the same time as the deformationcalibration of the outer walls of said tubular body.

A further object of this invention is to provide a method for themanufacture of self-lubricating and corrosion-resistant bearing unitsconsisting of two parts movable in relation to each other, such as abushing or the like provided with a shaft pin, whereby the bearer usedfor deformation calibration of said coating is constituting the shaftpin in the final bushing.

The invention is described in detail as follows with reference to apreferred embodiment shown in the accompanying drawings.

FIG. I shows a suitable means for performing the method proposedaccording to the invention,

FIG. 2 shows a suitable design for the inner coating used, and

FIG. 3 shows a final product consisting of a bushing and shaft pinmanufactured according to the invention.

FIG. 1 shows a calibrating mandrel l for calibration of a metal sheath 2by means of a bearer 3. The sheath is in this case intended to be usedas a bushing, the bearer 3 comprising the finished shaft pin for thebushing. Four designates a bearing foil of plastic or some otherwear-resistant material, to be applied on the inner sheath surface ofthe sleeve 2. Polytetrafluorethylene is particularly suitable for thispurpose.

Before the sleeve 2 is placed in the calibrating mandrel l the innersurface of the sleeve is provided with said bearing foil 4. For thispurpose the bearing foil may be coated with adhesive of curable type onthe side facing the inner surface of the sleeve 2, for example an epoxyresin or the like, or the adhesive may be applied on the inner side ofthe sleeve. The adhesive may be precured and the final curing is thenachieved in known manner by heating. The bearing foil is thus attachedinside the sleeve 2.

The sleeve 2 may consist of a mass produced tubular body which can beused immediately without any special external or internal machining. Thethickness of the bearing foil 4 depends on the predetermined clearancebetween the sleeve and the shaft pin 3 and should preferably be slightlythicker than said clearance so that a certain deformation is guaranteedto give the highest deformation under load.

In the example shown a shaft pin 3 is used as bearer which,

after the calibration process, is intended to serve as shaft pin in theunit manufactured. The shaft pin 3 is coated in a manner known per sewith a layer of plastic or some other wear-resistant material, suitablypolytetrafluorethylene.

The tolerance between the outer diameter of the coated shaft pin 3 andthe inner diameter of the sleeve 2 may be a few millimeters, suitably 23mm. The calibrating mandrel l is provided in known manner with aslightly conical inlet opening, narrowing towards the middle of thecalibrating mandrel.

For the calibration process the sleeve 2 is applied in the calibratingmandrel 1, after which the shaft pin 3 is placed down into the sleeve.The exterior of the sleeve is thus brought into contact with thecalibrating mandrel so that the sleeve is deformed to the desired outerdimension and at the same time obtains an extremely accurate calibrationdue to a deformation of the bearing foil between the shaft pin 3 and theinside of the sleeve 2. Any excess material obtained during thisdeformation calibration of the bearing foil 4 is pressed out at the endsof the sleeve after the calibration and can easily be removed.

When the adhesive has been cured the shaft pin can easily be pressed outof the sleeve because of the smooth coating layer existing between theinterior of the sleeve and the exterior of the shaft pin.

The product thus obtained comprises a self-lubricating bushing which iscompletely maintenance-free since both surfaces are coated and thuscompletely protected from corrosion and fitted to each other in acompletely novel manner.

The method proposed according to the invention thus offers extremelyaccurate tolerances both with respect to the external measurements ofthe sleeve and also with respect to the clearance existing between theshaft pin and the inside of the sleeve.

The shaft pin may also be provided with an oil coating instead of beingcoated with a suitable plastic layer.

What I claim is:

l. A method of applying a lubricating and friction-reducing layer on theinner surface of a tubular metallic body comprising the steps ofarranging a lubricating and friction-reducing coating on the innersheath surface of said tubular body, subjecting said coating to adeformation calibration by means of a bearer and at the same time duringsaid deformation calibration of said coating, subjecting the exterior ofsaid tubular body to a calibration by means of a calibrating mandrelhaving a slightly smaller diameter than the outer diameter of saidtubular body.

2. A method as set forth in claim I, wherein a shaft pin coated with alayer of friction-reducing material is used as bearer.

3. A method as set forth in claims I and 2 for manufacturing aself-lubricating and corrosion-resistant bearing unit consisting of twoparts movable in relation to each other, such as, for example a bushingor the like provided with a shaft pin, wherein said bearer used fordeformation calibration of the coating material comprises the shaft pinin the final bushing.

1. A method of applying a lubricating and friction-reducing layer on theinner surface of a tubular metallic body comprising the steps ofarranging a lubricating and friction-reducing coating on the innersheath surface of said tubular body, subjecting said coating to adeformation calibration by means of a bearer and at the same time duringsaid deformation calibration of said coating, subjecting the exterior ofsaid tubular body to a calibration by means of a calibrating mandrelhaving a slightly smaller diameter than the outer diameter of saidtubular body.
 2. A method as set forth in claim 1, wherein a shaft pincoated with a layer of friction-reducing material is used as bearer. 3.A method as set forth in claims 1 and 2 for manufacturing aself-lubricating and corrosion-resistant bearing unit consisting of twoparts movable in relation to each other, such as, for example a bushingor the like provided with a shaft pin, wherein said bearer used fordeformation calibration of the coating material comprises the shaft pinin the final bushing.